The unique failure behavior of Ni–Mo–Cr-Gd superalloy during hot compression at ultrahigh temperatures

The unique failure behavior of the Ni–Mo–Cr-Gd superalloy deformed at 0.01 s−1 and 0.5 strain with ultra-high temperatures has been investigated. The samples compressed at 0.01 s−1 and 0.5 strain are severely cracked at 1230 °C, and almost completely crushed at 1250 °C. The microstructure observations show that the divorced γ/Ni5Gd eutectic phase transforms into the lamellar γ/Ni5Gd eutectic phase, and the Ni5Gd phase disappears in the center of samples, especially at 1250 °C. Here, the eutectic transformation is attributed to the fact that the Ni5Gd phase melts and solidifies due to the temperature rise of local interface friction between the Ni5Gd phase and the γ matrix. Furthermore, the severe failure of samples and the unexpected disappearance of the Ni5Gd phases were ascribed to the interconnected localized melting regions of the Ni5Gd phase.